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[198.145.29.99]) by mx.google.com with ESMTPS id 67si19358528plf.382.2019.05.14.12.12.46 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 14 May 2019 12:12:46 -0700 (PDT) Received-SPF: pass (google.com: domain of gregkh@linuxfoundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=toauLP82; spf=pass (google.com: domain of gregkh@linuxfoundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8AFDD20675; Tue, 14 May 2019 19:12:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557861166; bh=Dx8fO3TTAFVbhjdjmVSXfGcWo/4xM9XJT2npi4xsxtc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=toauLP82s6SvK8V1KkHf5COFmXqXrCdzvWsSIFzpnOMz7HsK8pGBWSn2riYujnQm3 UI2pj0XEpWNT5f3qUGUCkuemRm2ajtG8i/wdw9VqAHsfrUmDKzFPIQ/O90P7kZZGPL U0nCodj8lpkzjPsBWsi9XCyThfy2fiK8twsrFumQ= Date: Tue, 14 May 2019 21:12:43 +0200 From: Greg Kroah-Hartman To: Dan Williams Cc: akpm@linux-foundation.org, Logan Gunthorpe , Bjorn Helgaas , Christoph Hellwig , "Rafael J. Wysocki" , Ira Weiny , linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-mm@kvack.org Subject: Re: [PATCH v2 1/6] drivers/base/devres: Introduce devm_release_action() Message-ID: <20190514191243.GA17226@kroah.com> References: <155727335978.292046.12068191395005445711.stgit@dwillia2-desk3.amr.corp.intel.com> <155727336530.292046.2926860263201336366.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155727336530.292046.2926860263201336366.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: Mutt/1.11.4 (2019-03-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, May 07, 2019 at 04:56:05PM -0700, Dan Williams wrote: > The devm_add_action() facility allows a resource allocation routine to > add custom devm semantics. One such user is devm_memremap_pages(). > > There is now a need to manually trigger devm_memremap_pages_release(). > Introduce devm_release_action() so the release action can be triggered > via a new devm_memunmap_pages() api in a follow-on change. > > Cc: Logan Gunthorpe > Cc: Bjorn Helgaas > Cc: Christoph Hellwig > Cc: Greg Kroah-Hartman > Cc: "Rafael J. Wysocki" > Reviewed-by: Ira Weiny > Signed-off-by: Dan Williams > --- > drivers/base/devres.c | 24 +++++++++++++++++++++++- > include/linux/device.h | 1 + > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/devres.c b/drivers/base/devres.c > index e038e2b3b7ea..0bbb328bd17f 100644 > --- a/drivers/base/devres.c > +++ b/drivers/base/devres.c > @@ -755,10 +755,32 @@ void devm_remove_action(struct device *dev, void (*action)(void *), void *data) > > WARN_ON(devres_destroy(dev, devm_action_release, devm_action_match, > &devres)); > - > } > EXPORT_SYMBOL_GPL(devm_remove_action); > > +/** > + * devm_release_action() - release previously added custom action > + * @dev: Device that owns the action > + * @action: Function implementing the action > + * @data: Pointer to data passed to @action implementation > + * > + * Releases and removes instance of @action previously added by > + * devm_add_action(). Both action and data should match one of the > + * existing entries. > + */ > +void devm_release_action(struct device *dev, void (*action)(void *), void *data) > +{ > + struct action_devres devres = { > + .data = data, > + .action = action, > + }; > + > + WARN_ON(devres_release(dev, devm_action_release, devm_action_match, > + &devres)); What does WARN_ON help here? are we going to start getting syzbot reports of this happening? How can this fail? thanks, greg k-h